Batteries generate electric power by using materials capable of electrochemical reactions at positive and negative electrodes. For example, a rechargeable lithium battery generates electricity due to a change of chemical potentials when lithium ions are intercalated/deintercalated at positive and negative electrodes.
The rechargeable lithium battery includes a material that can reversibly intercalate/deintercalate lithium ions as positive and negative active materials, as well as an organic electrolyte solution or a polymer electrolyte charged between the positive and negative electrodes.
As for a negative active material for a lithium rechargeable battery, various carbon-based materials such as artificial graphite, natural graphite, and hard carbon that are capable of intercalating and deintercalating lithium ions have been used.
As for a positive active material for a lithium rechargeable battery, a lithium metal composite compound is used. For example metal composite oxides such as LiCoO2, LiMn2O4, LiNiO2, LiNi1−xCoxO2 (0<x<1), LiMnO2, LiFePO4, and the like, have been researched.